This compiler on SYSTEM2 is happy. but second way does not look correct to me and compiler on system 1 complains about it. Which is the correct way to allocate memory?
If first one is correct then what should i look in for to avoid this error? Could this be an issue with compiler on SYSTEM2? If i use second method on SYSTEM2 code segfaults during malloc.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
typedef struct mystruct1 {
int a;
int b;
I'm trying to use a structure in union in the following format:
Code: union data { unsigned char All[10] ; struct data_pkt { unsigned char ack; unsigned short status; unsigned short data_length; unsigned char Data[5]; }format; }adb; adb.
All has 10 bytes which is equivalent to the structure bytes. ie 6 bytes if unsigned char and 2 short i.e 4 bytes. Thus total 10 bytes is given to adb.All. When I print the struct size I get 12 bytes. This creates problem in obtaining data in union. According to the program:
adb.format.ack should have the address of adb.All[0] adb.format.status should have the address of adb.All[1] adb.format.data_length should have the address of adb.All[3] adb.format.Data[0] should have the address of adb.All[5]
But in actual case this is how memory is allocated:
adb.format.ack assigned to the address of adb.All[0] adb.format.status assigned to the address of adb.All[2] adb.format.data_length assigned to the address of adb.All[4] adb.format.Data[0] assigned to the address of adb.All[6]
BIT_FIELD_TYPE; Except, what I'd like to do is to replace all the single-bit elements in the bits structure with a single statement that creates an array of, say, 32 values. The clear advantage of this is that it could be traversed using an iterator, ...
Code: main() { BIT_FIELD_TYPE foo; unsigned int i; ... for (i = 0; i < n; i++) { ... (print out foo.bits.b[i]) ... }
So far, I've not figured out a way to do it, either as an array, or using a pointer to iterate through the individual bits.
I have kept dummy as the data to be aligned.I will update hours, minutes, and seconds , but will not use dummy in any case. If I don't initialize 'dummy' does it make any errors ? Do I need to initialize hours, minutes, seconds as well before I use the structure ? If so is there any particular reason ?
Code: typedef struct _a { int id; } a; typedef struct _b { a my_a; my_a.id = 1; // error: expected specifier-qualifier-list before "my_a" } b;
I get error: expected specifier-qualifier-list before "my_a"
I must set the id for the kind of struct created inside the struct def because main() will be casting based on this id. Thats how I will know which structure b contains by it's id, there could be hundards of different structs with different values I will cast to the correct one and know it's members by it's id. How do I ?
I have a question regarding composition and accessing members "deep" inside the composed structure. For example;
class A { private: int m_myInt; public: int myInt() const {return this->m_myInt;}; void myInt(int newInt) {this->m_myInt = newInt;};
[Code] ....
Now, from somwhere I have access to an object of type B where I want to update the A::m_myInt. How would you do this without "breaking" the whole purpose of private/public members?
B myB; myB.m_a.myInt(3); // Not allowed, and not desireable
I thought about implementing access through functons kind of like;
A & B::a() {return this->m_a;}; myB.a().myInt(3);
but I'm worried that this exposes my B::m_a-object too much. This would allow
myB.a() = A(); , right?
The following is a more desireable way of acces, but doesn't work for updating;
A const & B::a() {return this->m_a;}; myB.a().myInt(3); //Disallowed? myInt(int) is non-const.
What about this? Is this a good way of doing it?
class A { private: int m_myInt; public: int myInt() const {return this->m_myInt;};
[Code] ....
I guess it works? It would lead to a lot of data shuffling in case of larger sub-components.I would really like to do the following without exposing my components so much:
I'm trying to call a function via a function pointer, and this function pointer is inside a structure. The structure is being referenced via a structure pointer.
Code:
position = hash->(*funcHash)(idNmbr);
The function will return an int, which is what position is a type of. When I compile this code,
I get the error: error: expected identifier before ( token.
Is my syntax wrong? I'm not sure what would be throwing this error.
error: request for member 'character' in '* ptr', which is of non-class type 'datastructure*' error: request for member 'character' in '* ptr', which is of non-class type 'datastructure*'
These errors are related to " *ptr->character='a'; printf("Ptr: %c",*ptr->character); "
I want to access "character" data inside the structure "trial" by a pointer to pointer "ptr" inside function "function",but I couldn't find a way to do this.
How I could use unions to combine registers elegantly. For example I have the 8 bit registers B and C & I have opcodes that work on each independent register such as add b, c, which is simple, but then I also have opcodes that work on both of them as if they're one like ld a, bc. I know I could go about that by just masking them together but I've seen it done with unions before & it made everything so much more simple.
In the current code,We are using pointer of union and assigning value.
class sample { union { short *two_int; int *four_int; double *eight_real; char *one_ascii; // void *v; }; }
Than we assign value in following way.
sample.four_int[0] = (x + xoff); ( x and xoff and y and yoff all are integer) sample.four_int[1] = (y + yoff);
Than we write data into file. it was working fine into 32 bit machine but it is not working 64bit machine. When I compare data and found that data is divided by 4. For Ex The File generating from 32 bit machine contain 80 than 64 bit . File contain 20.
I have made VGA emulation with registers and memory in my emulator. But for some reason the writes to the union array with CPU data (register 0-8 of the VGA's Graphics Controller Registers, referenced with <GRAPHREGS>.DATA[index]) don't reflect on the union's data.
typedef union __attribute__((packed)) { byte DATA[9]; //9 registers present! struct //Contains the registers itself! { //Set/Reset Register (index 00h) union {
[code]...
what's going wrong? Have I made an error in the registers?
(In this case I write to register <GRAPHREGS>.DATA[8] (which should be the <GRAPHREGS>.REGISTERS.BITMASKREGISTER)), but the BITMASKREGISTER stays 0, while DATA[8] gets the correct value.
typedef union UUID { unsigned char byte[16]; /**< Array of 16 bytes. */ unsigned int ll[2]; /**< Array of two 64-bit words. */ } UUID;
[Code] ......
The compiler complains thus
$ g++ union.cpp union.cpp: In function "int main()": union.cpp:15:17: warning: extended initializer lists only available with -std=c++0x or -std=gnu++0x union.cpp:15:17: warning: extended initializer lists only available with -std=c++0x or -std=gnu++0x union.cpp:15:17: error: no match for "operator=" in "entry.EntryHeader::uuid = {0, 0, 0, 2}" union.cpp:1:20: note: candidate is: UUID& UUID:perator=(const UUID&)
How do I go about assigning values to this union in C++.
Classes can be defined not only with keyword class, but also with keywords struct and union.
The concepts of class and data structure are so similar that both keywords (struct and class) can be used in C++ to declare classes (i.e. structs can also have function members in C++, not only data members). The only difference between both is that members of classes declared with the keyword struct have public access by default, while members of classes declared with the keyword class have private access. For all other purposes both keywords are equivalent.
The concept of unions is different from that of classes declared with struct and class, since unions only store one data member at a time, but nevertheless they are also classes and can thus also hold function members. The default access in union classes is public.
The above is a statement taken from a C++ tutorial. So I understand classes a bit better now but the above quote doesnt make too much sense. Is it saying that you can have a class within a class?
This is what I'd expect, but I can't find any evidence online in C standards or elsewhere:
1. Works as expected, sets the value of a.num1 to 2. 2. Works as expected, sets the value of b.num1 to 2. 3. Works as expected, sets the value of a.num2 to 2. 4. Works as expected, sets the value of b.num2 to 2. 5. Works as expected, sets the value of b.num1 to 2. 6. Works as expected, sets the value of a.num1 to 2. 7. Works as expected, sets the value of b.num1 to 2. 8. Crashes/Memory Corruption, attempted to alter memory outside struct. 9. Works as expected, * ss1 == * ss2 10. Crashes/Memory Corruption, attempted to alter memory outside struct.
I've tested simular code on my machine (Xubuntu 14.04LTS compiled with gcc on -O3) and it appears to be reliable, given that you stick with acessing the type tagged in the struct or the common initial union struct members (in this case num1).
union { short *two_int; int *four_int; double *eight_real; char *one_ascii; // void *v; };
We have write function which write into file.
fwrite (r.one_ascii, 1, i, outstr);
I found one thing,When we write function, we fill only four int in following way.
r.four_int[0] = x + xoff; r.four_int[1] = y + yoff;
So my question,we fill four_int but write one_ascii only.As is it union of pointer. So it does not matter. I am using 64bit machine and do not have any issue in 32 bit machine.
The program is to find intersection,union and difference of two sets. The program take the input correctly but after it crashes with the message that some exe is not working...
Code: #include<iostream> using namespace std; void Input(int *A, int*B, int size1, int size2) //input function {
I'm trying to come up with the union of two Vector ADT bags, so I have to overload the '+' operator, but I'm getting a bunch of error messages saying:
VectorBag.cpp: In instantiation of ‘VectorBag<ItemType> VectorBag<ItemType>::operator+(VectorBag<ItemType>) [with ItemType = int]’: proj2.cpp:161:42: required from here VectorBag.cpp:81:24: error: no match for ‘operator[]’ (operand types are ‘VectorBag<int>’ and ‘int’) newBag.add(anotherBag[i]); ^ Here is the function to overload the operator:
template<class ItemType> VectorBag<ItemType> VectorBag<ItemType>::operator+(VectorBag<ItemType> anotherBag) { VectorBag<ItemType> newBag; for (int i = 0; i < anotherBag.getCurrentSize(); i++) newBag.add(anotherBag[i]); }
The add() function is pre-defined by me somewhere else in the code. It basically does push_back().
I'm trying to union eleven tables to call out data. Parent table is 'Events', child tables are 'SR1Laptimes', 'SR2Laptimes' and so on (there are ten SR... tables). Primary key in all tables is EventName. Parent/Child relationship is Events.EventName/SR1Laptimes.EventName etc All tables that start with SR have the same Schema. I'm trying to call out MIN(Q1) across all table but first need to Union them I believe. Here is my code.
myCommand.CommandText = "SELECT MIN(Q1), MIN(Q2), MIN(Q3), MIN(Q4), MIN(LaptimesMinutes), MIN(LaptimesSeconds) FROM (SELECT * FROM Events UNION ALL SELECT * FROM SR1Laptimes UNION ALL SELECT * FROM SR2Laptimes) WHERE (Events.Track = @track) AND (Events.Number = @number) AND (Events.Rider = @rider)"; myCommand.Parameters.AddWithValue("@track", analysisTrackComboBox.Text); myCommand.Parameters.AddWithValue("@number", analysisNumberComboBox.Text); myCommand.Parameters.AddWithValue("@rider", analysisRiderComboBox.Text);
I`ve wrote a function for my utility to XOR char* buffer by a key, then to reverse it with the same key. Here is the code, it`s simple enough:
Code:
static inline char* XOR_buffer(const char* d, const char* k ) { char *newstr = (char*) malloc(sizeof(char)* strlen(d)); newstr[0]=''; printf("%d is size of string ", strlen(d)); char *begin = newstr; char* ret = begin; int len = strlen(k); }
[code]....
The lengh of the string is reduced by the second XOR call. You can try it out, just define XORDBG to view the error message in the second pass to the buffer.
